1. Field of the Invention
The invention relates to implanted apparatus for dispensing medical or physiological substances. More specifically, the invention relates to a device and method principally concerned with using the control circuitry in an implanted medication system to provide medication programs responsive to the needs of the patient at particular times.
2. Description of the Prior Art
A review of prior art practices with regard to dispensing medical substances internally of the body has previously been given in my prior U.S. Pat. No. 3,692,027 to which reference is made. Also, a summary of such related prior art practices is given in my copending application, Ser. No. 463,262, now U.S. Pat. No. 3,923,060, to which reference is also made. The general background of the prior art is believed to have been also described or cited in my U.S. Pat. No. 3,923,060 and otherwise adequately explained in my prior patent and copending application and, therefore, will not be repeated here.
The present invention is primarily directed to devices and methods for dispensing substances internally of the body and which in some way utilize implanted components whose operational modes can be controlled externally of the body. So far as I am aware, my prior U.S. Pat. No. 3,692,027 provides the first teaching of a self-powered device which can be implanted and which is adapted to dispense medical substances in premeasured doses at specific intervals over a long period of time. The device and method of my prior U.S. Pat. No. 3,692,027 has been improved upon by the subject matter of my copending application, now U.S. Pat. No. 3,923,060, by providing means for sensing internal body conditions and for evaluating the sensed data in order to control both the conditions under which and the kind of dispensing which takes place.
In U.S. Pat. No. 3,923,060 there is described for one embodiment a logic flow chart for an implanted discrete electronic component medication dispensing system and an externally accessible switch which enables the implanted control circuit configuration to be changed by a needle-switch operator located externally of the body. Thus, there is provided a means for changing the implanted circuit configuration to vary the control system which controls the manner in which the stored substances are dispensed. Much of the referred to description of the copending application is later repeated in the specification of this application and is noted here primarily for the purpose of pointing out that the present invention is concerned with both the needle operator-rotary switch technique for extracorporeal circuit control as well as with a dramatically improved means and method for circuit modification of implanted dispensing control circuitry to provide a treatment more compatible with actual need.
The emphasis of the present invention is thus directed to providing implanted control circuitry for controlling the dispensing of medication and which circuitry can be modified by means located external of the body. In this regard, it may be noted that U.S. Pat. No. 3,527,220 has previously taught the practice of implanting a medication storage container, a pump connected to pump the medication from the container to a site within the body, and means by which the pump can be powered through an extracorporeal magnetic field. This patent reference also teaches the practice of having an implanted switch whose action can be controlled by an extracorporeal magnetic field. The system taught by U.S. Pat. No. 3,527,220, however, basically has only an on-off capability and no programming capability. That is, there is no choice of circuit configurations which can be modified by an extracorporeal control to provide a variety of programs for dispensing the medication. The system of U.S. Pat. No. 3,527,220 also noticeably lacks any means for sensing internal body conditions and using the sensed data as a means for controlling the dispensing of medication.
With respect to extracorporeal control of implanted programmable circuitry, U.S. Pat. No. 3,833,005 illustrates a cardiac "pacemaker" type device which uses an extracorporeal transmitter to provide control signals to the pacemaker receiver and from there to the control circuitry. The control circuitry includes memory, counting and logic circuitry which provides a simple programming capability for rate and amplitude control for pacemaking purposes but has no medication dispensing mechanism.
The prior art practices concerned with implanting artificial and replacement material organs should also be noted. Of particular interest to the present invention is the recent development in Canada of a non-implanted but computerized artificial pancreas in which blood sugar is monitored and insulin or dextrose is delivered according to need. This development is also reported in a Post Times Service news release of Apr. 18, 1974 and is described in the Medical Tribune and Medical News issue of Oct. 9, 1974, and the articles suggest the possibility of developing a miniaturized, implantable artificial pancreas.
Another prior art development related to the present invention concerns the availability of what are called microprocessors. In this regard, reference may be made to an article appearing in the Apr. 18, 1974 issue of Electronics Magazine. As explained in this article, the availability of a microprocessor drastically reduces the cost and also the size of the circuitry required to provide programming capability in miniaturized circuits. By adding appropriate memory devices to the microprocessor and applicable input and output circuits, there becomes available a micro-miniaturized programmable circuit with a versatile programming characteristic, highly adaptable input/output system capabilities, minimum parts count and easy expansion through modular architecture. The current Fairchild F-8 microprocessor series provides such a system. From the foregoing, it can be seen that while the implanted system and method for dispensing medical substances, as taught in U.S. Pat. No. 3,923,060, provides a unique system and a method for a limited programmable system for periodically evaluating selected states of the body and dispensing medical substances accordingly while leaving the patient ambulatory, the present invention recognizes that further improvements could be made by embodying a micro-miniaturized more adaptable programming capability and a system and method which would lend itself to extracorporeal control of such capability and to reprogramming.